The present invention pertains generally to electronic instrumentation and more particularly to isolators and event stackers. In various instrumentation schemes, it is necessary to provide a recording system capable of reproducing a multiplicity of event signals. Existing recording systems have generally lacked channel capacity for recording a large number of signals, e.g., as many as 24 on a single recorder. As a result, more than one multiple channel recorder has been required to record this many event signals. Since these recorders are expensive, a system has been needed which will record numerous event signals upon a single recorder channel, thereby reducing the overall number of recorders required. Prior systems which have provided such coding systems have lacked the capability of electrical isolation between the encoding device and the equipment under test. Consequently, electrical feedback signals have often times caused damage to this electrical equipment. In addition, a convenient method for displaying the presence of an event signal to allow the operator to visually perceive the existence of the signal prior to being encoded has not been provided by the prior art devices.